If it already has long and healthy roots, I doubt there is any benefit. It would probably be more beneficial to just pot it up, and keep it watered and fertilized.

nope rooting hormone will not help established plants. it's just for roots on wounds and nodes. don't waste your hormone go with something like a 5-20-10 fertilizer and use as directed more is not better. this is also a good fert mid season around the first of june as it will boost your fig production as well as establish roots on young plants not old enough to produce figs. if a young fig does have figs pick them off the first year and it will put more power into the plants thus making it a stronger, well rooted plant that's less susceptible to disease. beware of fertilizers with high first number like 20-10-10 or 10-5-5 late in the season as it will give you a flush of growth and a bunch of die back come winter and possibly death. hope this helps.